Impact of traffic growth on air quality: a case study of Delhi, India.

Poor air quality in ever-growing cities is a worldwide problem. This paper presents the correlation between rising vehicle numbers – particularly powered two-wheelers – and air quality and health in Delhi, India. Concentrations of carbon monoxide, nitrogen oxides and sulfur dioxide were measured in the city over 2 years. Peak values occurred in winter months and those of carbon monoxide and nitrogen dioxide were over double national air quality limits. Measures to improve urban air quality are proposed.